License-based cryptographic technique, particularly suited for use in a digital rights management system, for controlling access and use of bore resistant software objects in a client computer

Abstract

A technique for imparting substantial break-once-run-everywhere (BORE) resistance to passive and active software objects, and for controlling access and use of resulting protected objects by a client computer ( 400 ). Specifically, a relatively large number, n, of identical watermarks ( 1720 ) are embedded throughout a software object ( 1700 ), through use of n different secret watermark keys to form a protected object, with each key defining a pointer to a location in the protected object at which a corresponding watermark appears.

1. A computer-readable medium having computer-executable instructions for performing steps comprising:
 utilizing an enforcer contained within a digital rights management system, for controlling use of watermarked software objects, wherein the enforcer stores a predefined watermark key which defines a specific one of a plurality of identical watermarks embedded in the watermarked software object with different watermark keys to be used by the enforcer in subsequently controlling use of each one of said watermarked software objects, and wherein the predefined watermark key expires after a predefined period of time elapses since said predefined watermark key was initially stored in the enforcer; 
 establishing a network connection to a server if the predefined watermark key is not possessed; 
 issuing a request to the server for a new watermark key; 
 storing the watermark key received from the server for subsequent use in controlling access to watermarked software objects; 
 selecting one of a predefined plurality of predetermined watermark keys for use in controlling access to the software watermarked objects as the watermark key; and 
 downloading the watermark key to the client computer. 
 
   
   
     2. The computer readable medium of  claim 1  having further computer instructions for connecting to a secure connection. 
   
   
     3. The computer readable medium of  claim 2  having further computer instructions for associating the server with a publisher of any one of the watermarked software objects or a vendor of said one object, or a watermarking authority. 
   
   
     4. The computer readable medium of  claim 1  having further computer instructions for encrypting the watermark key using the public key of the client computer so as to yield the encrypted key; downloading the encrypted key to the client computer as the watermark key upon receipt of the watermark key; decrypting the encrypted key using a private key associated with the client computer so as to yield a decrypted key; and storing the decrypted key as the watermark key. 
   
   
     5. The computer readable medium of  claim 4  having further computer instructions for connecting to a secure connection. 
   
   
     6. The computer readable medium of  claim 5  having further computer instructions for associating the server with a publisher of any one of the watermarked software objects or a vendor of said one object, or a watermarking authority. 
   
   
     7. A digital rights management system comprising:
 a processor means; 
 a means for enforcing digital rights management of watermarked software objects utilizing an enforcer executed on the processor, wherein the enforcer stores a predefined watermark key which defines a specific one of a plurality of identical watermarks embedded in the watermarked software object with different watermark keys to be used by the enforcer in subsequently controlling use of each one of said watermarked software objects, and wherein the predefined watermark key expires after a predefined period of time elapses since said predefined watermark key was initially stored in the enforcer; 
 a means for establishing a network connection to a server if the predefined watermark key is not possessed; 
 a means for issuing a request to the server for a new watermark key; 
 a means for storing the watermark key received from the server for subsequent use in controlling access to watermarked software objects; 
 a means for selecting one of a predefined plurality of predetermined watermark keys for use in controlling access to the software watermarked objects as the watermark key; and 
 a means for downloading the watermark key to the client computer. 
 
   
   
     8. The digital rights management system of  claim 7  further comprising a means for connecting to a secure connection. 
   
   
     9. The digital rights management system of  claim 8  further comprising a means for associating the server with a publisher of any one of the watermarked software objects or a vendor of said one object, or a watermarking authority. 
   
   
     10. The digital rights management system of  claim 7  further comprising a means for encrypting the watermark key using the public key of the client computer so as to yield the encrypted key; downloading the encrypted key to the client computer as the watermark key upon receipt of the watermark key; a means for decrypting the encrypted key using a private key associated with the client computer so as to yield a decrypted key; and a means for storing the decrypted key as the watermark key. 
   
   
     11. The digital rights management system of  claim 10  further comprising a means for connecting to a secure connection. 
   
   
     12. The digital rights management system of  claim 11  further comprising a means for associating the server with a publisher of any one of the watermarked software objects or a vendor of said one object, or a watermarking authority.